High and low temperature warning device

ABSTRACT

Two or more thermostats are positioned about a storage structure being monitored with at least one thermostat switching at a predetermined low temperature and at least one thermostat switching at a predetermined high temperature. A power supply portion receives either standard A.C. line power or D.C. power from an auxilliary battery, and provides lower voltage A.C. power to the thermostats when A.C. line power is present, and automatically provides D.C. power from the battery when A.C. power fails. The low and high temperature thermostats are connected respectively to low and high temperature signal lamps remote from the thermostats, providing distinctive visual signals when the thermostats switch at the temperature extremes and power is supplied to the lamps. The thermostats are also connected to an audio signal portion which produces a tone when electrical power is supplied to it. When A.C. power is available, differing tones are produced depending on whether power is being supplied through the low temperature thermostat or through the high temperature thermostat. Test circuits are provided to allow periodic checks of the electrical condition of the device to be made.

Bennetts [451 Oct. 7, 1975 HIGH AND LOW TEMPERATURE WARNING DEVICE [76] Inventor: John F. Bennetts, PO. Box 127,.

1707 Neva Road, Antigo, Wis. 54409 [22] Filed: Jan. 17, 1974 [21] Appl. No.: 434,072

[52] US. Cl. 340/227.1; 340/214; 340/384 E [51] Int. Cl. G08B 19/00 [58] Field of Search..... 340/227.1, 420, 214, 227 R,

[56] 7 References Cited UNITED STATES PATENTS 2,663,860 12/1953 Maclnnes et a1. 340/227.1 2,753,548 7/1956 Gates 340/227 R 2,994,858 8/1961 Coffer 340/227.1 3,056,120 9/1962 Mobarry.... 340/227.1 3,295,120 12/1966 Witchie..... 340/227 R 3,380,045 4/1968 Lindberg 340/227 R Primary ExaminerGlen R. Swann, III Attorney, Agent, or Firm-Theodore J. Long; John M.

Winter; Harry C. Engstrom [57] ABSTRACT Two or more thermostats are positioned about a storage structure being monitored with at least one thermostat switching at a predetermined low temperature and at least one thermostat switching at a predetermined high temperature. A power supply portion receives either standard A.C. line power or D.C. power from an auxilliary battery, and provides lower voltage A.C. power to the thermostats when A.C. line power is present, and automatically provides D.C. power from the battery when A.C. power fails. The low and high temperature thermostats are connected respectively to low and high temperature signal lamps remote from the thermostats, providing distinctive visual signals when the thermostats switch at the temperature extremes and power is supplied to the lamps. The thermostats are also connected to an audio signal portion which produces a tone when electrical power is supplied to it. When A.C. power is available, differing tones are produced depending on whether power is being supplied through the low temperature thermostat or through the high temperature thermostat. Test circuits are provided to allow periodic checks of the electrical condition of the device to be made.

3 Claims, 1 Drawing Figure US. Patent 05:. 7,1975

HIGH AND LOW TEMPERATURE WARNING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains generally to the field of warning systems which monitor temperatures at one or more locations in a structure and provide signals at a location remote therefrom.

2. Description of the Prior Art Several systems have been developed which monitor temperature in a warehouse or other storage structure and provide a warning signal at some remote location where a human attendant is available. These systems are usually intended primarily to provide a warning if fire is detected, or to automatically turn on a sprinkler system. Special problems are encountered with the temperature control of large, poorly insulated structures which are used for the storage of perishable commodities such as farm crops. Many crops, such as potatoes, cannot tolerate freezing and yet are stored in warehouses or barns which may not have automatically controlled heating systems. if any at all. Damage to crops in such structures from freezing can be avoided if temporary heaters are employed as necessary, and in a timely fashion. The known automatic temperature warning systems have not generally been used for the typical crop storage operation because of their prohibitive expense. However, manual monitoring of temperatures throughout a storage structure is also expensive in terms of the man-hours required, with this burden being especially heavy on small storage operations such owner operated farms.

SUMMARY OF THE INVENTION I have invented an inexpensive yet highly reliable temperature warning device which provides a warning signal when temperatures in a structure being monitored are above or below a specified acceptable range. My warning device ordinarily operates on standard 1 volt alternating current (A.C.) power but automatically switches over to direct current (DC) power from an auxilliary battery when A.C. power fails. Any number of high temperature and low temperature thermostats may be used with my device, allowing monitoring of the temperatures throughout a large structure. The high temperature thermostat or thermostats activate a visual signal portion which produces a visual signal distinguishable by color and position from the visual signal which is activated by the low temperature thermostats. Both high and low temperature thermostats activate an audio signal portion which, when A.C. power is supplied, provides an audio signal which distinguishes be tween a high temperature and a low temperature warning. When DC power is supplied, the sound produced by the audio signal portion is identical for both high temperatures and low temperatures.

The reliability of my warning device is enhanced by multiple paralleled lamps in the visual signal portions and by the provision of test circuits which allow the electrical condition of the device to be checked.

Further objects, features and advantages of my invention will be apparent from the following detailed de-- scription taken in conjunctionwith the accompanying drawing showing a preferred embodiment of a high and low temperature warning device exemplifying the principles of my invention.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic circuit diagram of a temperature warning device embodying the principles of my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawing, a preferred embodiment of my high and low temperature warning device is shown generally at 10. The warning device customarily operates on standard alternating current (A.C.) power, preferably volt RMS at 60 Hz, as provided by the power lines 11 and 12 shown in the drawing. An alternate source of power for my warning device is provided by a battery 13 which preferably supplies 12 volt direct current (DC) power to the warning device through the power lines 14 and 15.

A power supply portion 6 of my warning device is adapted to be connected to and receive A.C. power from the power lines 11 and 12 and to be connected to receive a DC. power from the power lines 14 and 15. To provide means for periodically testing the battery 13, the power supply portion 16 includes a lamp l7 and pushbutton switch 18 in series which are connected across the lines 14 and 15, in parallel with the battery, as shown in the drawing. When the pushbutton 18 is depressed, the lamp 17 should light brightly if the battery is in proper condition. The power supply portion has a step-down or voltage reducing transformer 19 which has its primary side connected to the A.C. power lines 11 and 12. When the primary is supplied with l 15 volt RMS power, the secondary side of the transformer 19 preferably has output voltages of 8 volts RMS between the output lines 20 and 21 and 16 volts RMS between the output lines 21 and 22. A power-on" lamp 23 is connected between the lines 20 and 21 to indicate at the power supply whether A.C. line power is being supplied, since if A.C. power is interrupted, this lamp will cease burning.

The power supply portion 16 delivers electrical power to the remainder of my temperature warning device 10 through the output lines 20 and 21 and through a third output line 24. The voltage appearing between the output terminal lines 21 and 24 will be 16 volts RMS A.C. as long as A.C. power is being provided to the power supply portion 16, and will be 12 volts DC. as provided by the battery 13 whenever A.C. power is interrupted. The switching between A.C. and DC. power is accomplished by a double-pole double-throw relay 25. The relay coil 25a in therelay 25 is activated by the 1 15 volt A.C. power from the power lines 11 and 12, which is delivered to the coil 25a by a pair of conducting lines 26 and 27. When A.C. power is present, the coil 25a will be activated, thus drawing the relay switches 25b and 25cto their inward position, as shown in the drawing. In the inward position, the switch 25bconnects the lines 22 and 24, with 16 volts A.C. thus appearing between the lines 21 and 24, while switch 250 has no connection made to it in this inward position. When A.C. power is removed, the switches 25b and 250 will return to their normal or outward positions, thereby connecting the line 15 with the line 24 through the switch 251) and connecting the line 21 with the line 14 through the conducting line 28 and the switch 25c. The DC. battery voltage of 12 volts will thus appear between the power supply output terminal at least two temperature sensitive switches or thermostats, one such thermostat 29 switching at a low temperature to make a conducting path therethrough and the other thermostat 30 switching at a high temperature. The thermostats 29 and 30 preferably have adj ustable switching temperatures, with the high and low temperature settings being chosen by the user to give the protection desired. For example, a common use of my warning device is in warehouses where crops or other perishable commodities are stored. Since some crops, such as potatoes, cannot tolerate freezing, the low temperature thermostat 29 would be set to switch at a few degrees above 32F. Overheating, and of course fire, pose a danger to perishable commodities, and thus the high temperature thermostat would be set to switch at some high temperature near the upper to]- erance limits of the commodities. Such a high temperature thermostat may also be used to detect dangerous self-heating in stored crops such as hay. [t is apparent that several thermostats may be connected in parallel, with each thermostat placed as desired in a different part of the structure or area being monitored.

lt is preferable, although not necessary, that the thermostats 29 and 30 have single-pole double throw switches. Such construction allows monitoring of the condition of the thermostats and the wiring leading thereto by the use of built-in test circuits. As shown in the drawing, a lamp 31 and a pushbutton switch 32 are connected in series between the normal position of the thermostat 29 and the line 21, and a lamp 33 and a pushbutton switch 34 are connected in series between the normal position of the thermostat 30 and the line 21. Thus when the switches in the thermostats are in the normal positions shown in the drawing, closure of the pushbutton switches 32 or 34 will result in lighting of the lamps 31 or 33 respectively if the thermostats and the lines 24 and 21 are in proper condition.

When the low temperature thermostat 29 is in its switched position, at ambient temperatures below the predetermined lower limit, a conductive path connection is made by the thermostat 29 between the line 24 and a conducting line 35. Similarly, the high temperature thermostat switches at temperatures above its upper limit to make a conductive path connection between the line 24 and another conducting line 36. Two Low-Temperature amber 37a and 37b lamps are connected in parallel between the lines and 21; these lamps will thus light up when the thermostat 29 is in its low temperature switched position. The pair of identical incandescent lamps 37a and 37b is provided for increased reliability, with the lamps being selected to operate satisfactorily on either 16 volts A.C. or 12 volts D.C. Two similar High-Temperature red lamps 38a and 3812 are connected in parallel between the lines 36 and 21, with these lamps lighting when the high temperature thermostat 30 is in its high temperature switched position. It is apparent that any other visual indicators that operate on A.C. or DC. current could be substituted for the High-Temperature and Low- Temperature lamps. A Power-On lamp 39 is connected between the lines 20 and 21' to indicate whether A.C. power is being supplied to the system. The PowerOn lamp 39 and the warning lamps 37a, 37b, 38a, and 38b are grouped together in one location to form a visual signal portion 40 of my warning device 10. The visual signal portion 40 is preferably located in some accessible and easily visible position remote from the thermostats 29 and 30 to facilitate monitoring of the system by a watchman or other observer. 1

My high and low temperature warning device 10 also includes an audio signal portion 41 which is activated by the switching of the thermostats 29 and 30. The audio signal portion 41 is preferably located in a position remote from the thermostats 29 and 30 such as a residence or guardhouse where the sound produced by the audio signal portion will attract attention. The audio signal portion 41 has a diode 42 and an audio indicator 43 connected in series between the line 35 and the line 21 with the cathode 42a of the diode 42 connected to the line 35. A diode 44 and a capacitor 45 in parallel therewith are connected in series with the audio indicator 43 between the line 36 and the line 21. The cathode 44b of the diode 44 is connected to the line 36. The diodes 42 and 44 are provided so that direct'current is primarily supplied to the audio indicator. The diodes 42 and 44 are poled as shown to allow DC. power from the power supply portion 16 to blow through the diodes unimpeded.

Referring to the drawing, the switching of the thermostat 30 at high temperatures completes a first electrical circuit in series between the output terminal line 24, the thermostat 30, High Temperature visual indicator lamps 38a and 38b and the other output terminal line 21. Switching of the thermostat 29 at low temperatures completes a second circuit in series between the output terminal line 24, the thermostat 29, the Low Temperature" visual indicator lamps 37a and 37b and the output terminal line 21. When the thermostat 30 is switched at high temperatures, a third circuit is also completed in series between the output terminal line 24, the thermostat 30, the paralleled diode 44 and capacitor 45, the audio indicator 43 and the other terminal line 21. With the thermostat 29 switched at low temperatures a fourth circuit is completed in series between the output terminal line 24, the thermostat 29, the diode 42, the audio indicator 43, and the output terminal line 21. It is apparent that completion of these circuitswill result in activation of the visual indicators or audio indicator respectively only if electrical power is being supplied to the power supply portion 16.

The audio indicator 43 can be any sound producing device which is electrically activated by direct current such as a buzzer or a bell. However, it is preferable that the audio indicator be selected from one of the commercial devices having the characteristics of drawing very little current and producing sound volume in direct relation-to the magnitude of the voltage applied. With such a device employed as the audio indicator 43 and with A.C. power supplied, it is possible to produce a high temperature audio warning signal, which is distinguishable from the low temperature audio warning signal. This result is obtained because of the capacitor 45, preferably of capacitance one microfarad or greater, which is in .parallel with the diode 44. A.C.

voltage delivered to the audio indicator 43 through the switched low temperature thermostat 29 will be a filture thermostat 30, with the voltage across the audio indicator being substantially a half wave at 60Hz. The audio indicator will thus produce a high frequency tone modulated at 60Hz, which will be noticably different to the human ear than a steady tone. Of course, if DC. power is supplied to the audio indicator 43 through either the thermostat 29 or the thermostat 30, a steady tone will be produced which will not allow distinction between high or low temperatures but will provide a noticable warning signal.

It is understood that my invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as may come within the scope of the following claims.

I claim:

1. A high and low temperature warning device comprising:

a power-supply means adapted to be connected to a source of alternating current power and to a source of direct current power and having output terminals, said power supply means providing alternating current power at said output terminals when alternating current power is supplied to said power supply means and providing direct current power at said output terminals when direct current power is supplied to said power supply means and alternating current power is not supplied thereto;

b. high temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is above a predetermined high temperature;

c. low temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is below a predetermined low temperature;

d. a high temperature visual indicator providing a visible signal when supplied with electrical power;

e. a low temperature visual indicator providing a visible signal when supplied with electrical power;

f. audio indicator means for providing an audio signal in response to electrical power supplied thereto which varies in volume in direct relation with the voltage of said electrical power; and

g. circuit completion means for completing a first circuit in series between said power supply means output terminals, said high temperature thermostat means and said high temperature visual indicator, for completing a second circuit in series between said power supply means output terminals, said low temperature thermostat means and said low temperature visual indicator, for completing a third circuit in series between said power supply output terminals, said high temperature thermostat means and said audio indicator means, and for completing a fourth circuit in series between said power supply output terminals, said low temperature thermostat means and said audio indicator means.

2. The temperature warning device as specified in claim 1 including a paralleled diode and capacitor connected in series in said third circuit between said high temperature thermostat means and said audio indicator means, and including a diode connected in series in said fourth circuit between said low temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by said power supply to be substantially a half wave when power is supplied to said audio indicator means through said third circuit and to be substantially a smoothed half wave when power is supplied to said audio indicator means through said fourth circuit, said diodes being poled to allow direct current power from said power supply means to pass therethrough.

3. A high and low temperature warning device comprising:

a. high temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is above a predetermined high temperature;

b. low temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is below a predetermined low temperature;

0. audio indicator means for providing an audio signal in response to electrical power supplied thereto which varies in volume in direct relation with the voltage of said electrical power;

d. circuit completion means adapted to be connected to a source of electrical power for completing a first circuit in series between the source of electrical power, said high temperature thermostat means and said audio indicator means, and for completing a second circuit in series between the source of electrical power, said low temperature thermostat means and said audio indicator means;

e. a paralleled diode and capacitor connected in series in said first circuit between said high temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by a source of electrical power to be substantially a half wave; and

f. a diode connected in series in said second circuit between said low temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by a source of electrical power to be substantially a smoothed half 

1. A high and low temperature warning device comprising: a power supply means adapted to be connected to a source of alternating current power and to a source of direct current power and having output terminals, said power supply means providing alternating current power at said output terminals when alternating current power is supplied to said power supply means and providing direct current power at said output terminals when direct current power is supplied to said power supply means and alternating current power is not supplied thereto; b. high temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is above a predetermined high temperature; c. low temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is below a predetermined low temperature; d. a high temperature visual indicator providing a visible signal when supplied with electrical power; e. a low temperature visual indicator providing a visible signal when supplied with electrical power; f. audio indicator means for providing an audio signal in response to electrical power supplied thereto which varies in volume in direct relation with the voltage of said electrical power; and g. circuit completion means for completing a first circuit in series between said power supply means output terminals, said high temperature thermostat means and said high temperature visual indicator, for completing a second circuit in series between said power supply means output terminals, said low temperature thermostat means and said low temperature visual indicator, for completing a third circuit in series between said power supply output terminals, said high temperature thermostat means and said audio indicator means, and for completing a fourth circuit in series between said power supply output terminals, said low temperature thermostat means and said audio indicator means.
 2. The temperature warning device as specified in claim 1 including a paralleled diode and capacitor connected in series in said third circuit between said high temperature thermostat means and said audio indicator means, and including a diode connected in series in said fourth circuit between said low temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by said power supply to be substantially a half wave when power is supplied to said audio indicator means through said third circuit and to be substantially a smoothed half wave when power is supplied to said audio indicator means through said fourth circuit, said diodes being poled to allow direct current power from said power supply means to pass therethrough.
 3. A high and low temperature warning device comprising: a. high temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is above a predetermined high temperature; b. low temperature thermostat means for completing a conductive path therethrough if the ambient temperature thereof is below a predetermined low temperature; c. audio indicator means for providing an audio signal in response to electrical power supplied thereto which varies in volume in direct relation with the voltage of said electrical power; d. circuit completion means adapted to be connected to a source of electrical power for completing a first circuit in series between the source of electrical power, said high temperature thermostat means and said audio indicator means, and for completing a second circuit in series between the source of electrical power, said low temperature thermostat means and said audio indicator means; e. a paralleled diode and capacitor connected in series in said first circuit between said high temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by a source of electrical power to be substantially a half wave; and f. a diode connected in series in said second circuit between said low temperature thermostat means and said audio indicator means, thereby causing the voltage across said audio indicator means when alternating current is provided by a source of electrical power to be substantially a smoothed half wave. 